'88 F250 with 460. Had to replace water pump this past weekend and during this repair, I removed the air pump. I simply cut the hoses on the back of the pump and left the metal tubes in place. I also cut the rubber tube that goes to what looks like a black cylindrical thing that mounts on the inner fender well. I didn't do anything else and now the truck acts like it has a vacuum leak (probably does). What did I miss? I initially had a check engine light, but I temporarily restricted the freshly cut tubes by stuffing a rag in them and the light went off, but still runs rough. I would really appreciate any help you could give to a novice.

 

Anybody? please.

 

You need to plug the ports on the manifolds, or weld the tubes shut. Some guys pinch them together, but a full seal is best. You will also need to plug the line going to the cat, or remove it altogether. If you are in Cali, you'd better hook it back up, but if you don't, remove the cat, and put a piece of pipe in. Please don't put glass packs in either...

If you are still running the same belt with the pump in place, it is going to make a lot of noise under the hood. I removed mine and measured the length of belt I needed, and picked one up at napa.

 

Thanks cbakker! I have removed the pump altogether so no noise annoyance under the hood. So if I understand correctly, I can simply plug the two steel tubes that came from the pump and that should be adequate? I no longer have a CAT, and the tubes (there are two) that used to go to it are rusted and simply hanging under the truck. Can these just be cut shorter or do they need plugging as well? For my own knowledge, can the open CAT tubes allow the engine to have vacuum-like prblems?

Help is REALLY appreciated!

 

The tubes that go down to the cats are of no consequence so you cut them shorter, but everything attached to the engine upstream of the O2 sensor must be sealed so no fresh air gets in or it will screw with the O2 sensor readings

 

I am a fan of removing the air tubes from the cylinder heads and putting in some proper plugs. Those tubes weren't meant to handle the temps or gases they will now see. It will eventually corrode away until you have another exhaust leak, only now the leak will be near the firewall. You might not keep the truck long enough to experience this, but it will happen.

 

It's a mess now.I can't get this thing to run right at all. It's hard for me to even tell where the tubes enter the head. Its not at all visible. The lines from the vacuum canister no longer go to anything as I have disconnected them from the solenoid. I get an intermittent check engine light and the truck stumbles BAD. I see mention of two solenoid valves (TAB and TAD) on the forum but I can only find one (unless the EGR solenoid is one of them) Is the fact that the heads have not been plugged causing this condition. My AIR pump was going bad (bearing) and the cat was gone from previous owner but otherwise my truck ran great prior to this. Did I kill it?

 

If anything, I think the computer is reacting to the missing air that is supposed to be injected in the exhaust port. I've never disconnected the air pump from a fuel injected engine, so I don't know how much effect it has.

 

If the thermactor plugs on the back of the head were not plugged, would my truck run like garbage?

 

No. There is a check valve in the thermactor tubing that "should" prevent backflow of exhaust gases. You will be ok for a while, but the plugs are what I would do if it were my vehicle. They are difficult to install with the engine in the truck.

If your vehicle has an O2 sensor in the exhaust stream, I think that removing a source of fresh oxygen may upset the computer somewhat. I haven't removed mine, so I don't know for sure. Removing the air pump is a popular thing to do, so it may not make that much difference.

The things you have labeled "these were connected" do look like vacuum lines to me. Plug those and see if it makes a difference. You should be able to hear a vacuum leak that is big enough to change the way an engine runs.

 

Those tubes in the photo were plugged in when the air pump was installed, but the other end of the lines went to the vacuum solenoid. Everyone says there should be two vacuum solenoids, but I can only find one. The EGR is still hooked up. I have crawled around under the truck with a flashlight felt around the back of the heads and I cannot see or feel any evidence of any thermactor tubes. Maybe the previous owner has already removed the tubes, but I cannot feel any exhaust gasses leaking out. My truck is popping through the exhaust at part throttle and has a BAD rough idle. Did all trucks have a TAD and TAB solenoid from the factory? I'm in trouble here, I'm not sure I know how to fix this. Again, any advice or help is appreciated.

 

This thread has a pic of the TAB/TAD solenoids

https://www.ford-trucks.com/forums/1...ble-codes.html

 

This thread shows where the thermactor tubes go. Apparently they go into the exhaust manifold.

https://www.ford-trucks.com/forums/1...95-f250-2.html

 

Couldn't say but if its same as the 95' system (looks like it is but can't tell for sure just going by picture provided) it has the Thermactor Air Bypass "TAB" but not the Thermactor Air Diverter "TAD" reason you only have one solenoid to deal with not two.

Leave it electrically connected but plug vac line supply to it, computer will think all is well far as that goes.

(Again if same/similar to the 95) it had two tubes leaving the air pump, first goes directly to cat.

Second supplied Thermactor Air Bypass valve, computer command it either pumped air into back of both exaust manafolds or dumping air at fender to atmosphere.

It doesn't have a Thermactor Air Diverter (TAD) so did not divert between cat and manifolds (would have to see picture of your valve).

You're gonna have to sold plug those tube inlets into the back of both manafolds, gonna be a pain but the check valves and those thin wall tubes are only gonna last so long no air though them then big exhaust leak if don't already have one.

Sounds like already do stuffing rags down into tubes but that parts not exactly clear, if what it sounds like they'll be a source of flame in a day or two maybe not a good idea!

As stated by others yea you gotta plug those ports no two ways about it.

Doesn't sound like any of that is directly related to how it runs now though, well it is but not for reason directly related to eliminating the air system, sounds like you busted bunch of that old plastic vac line and now have couple leaks shouldn't have/didn't have when started.

Sounds like you unplugged something knocked plug wire off etc in the process changing the water pump and or while removing the air pump/cutting tubes/hoses to do it, either knocked something off or unplugged it missed it putting things back together.

Have you run the self test if for nothing else eliminate any such issues?

That and run down every vac line make sure none of them are broke. If you find they are brittle, probably will be, best bet replace all the plastic factory vac lines with rubber hose head off any present as well as future problems by doing so.

 

All you guys are great! I appreciate the time you take to help me. I crawled around my truck for many hours today and here is what I think I know. I do have only one valve and it seems that it functioned in the way danr1 described. It either allowed air to go to the front and rear of the CAT, or to the front of the CAT and to a muffler on the fender well. There are not thermactor tubes running into the rear of the heads, nor are there any running into the rear of the exhaust manifolds. Driver side has the EGR tube, but nothing else. Nothing on the passenger side. Strange huh? I will need to next go through all of the vacuum lines and check as there are no more tubes left to stuff rags into (LOL). When I changed the thermostat this past weekend, both bolts in the thermostat housing broke off. While I did not get too crazy, I did use a small propane torch to heat the remaining pcs. up in order to remove them. This are got pretty hot and it's near the distributor and perhaps a coolant sensor. I was really careful, but could this have ruined something?